1. Field of the Invention
The present invention relates to a method of diagnosing a motor vehicle battery.
2. Description of the Related Art
As is known, like any other component, batteries supplying the electrical power required for normal operation of a vehicle, such as a car, are subject, with use, to deterioration and malfunctioning. A faulty battery may be incapable of starting the engine or adequately powering all the connected user devices, which therefore operate poorly. Very often, a vehicle equipped with a battery in poor condition cannot be run at all, and, since the user is normally unable to predict malfunctioning of the battery, no servicing is carried out until a fault actually occurs.
By way of a solution to the problem, diagnosis methods have been devised to determine the charge status of the battery and signal any anomalous operating conditions, so that appropriate servicing may be carried out in time. More specifically, the diagnosis methods devised so far are based on measuring the internal resistance of the battery, which, as is known, is related to various factors, including ageing and the charge of the battery. That is, internal resistance is measured in predetermined battery conditions, is compared with a nominal reference value, and, if a significant difference is detected, an alarm signal is generated.
Known methods, however, have several drawbacks. For the necessary measurements to be made, the battery and/or control unit supervising operation of the engine must be equipped with sensors. More specifically, to measure the internal resistance of the battery, both a voltage and a current sensor are required, whereas one sensor would be more preferable. Using two sensors not only increases cost but also increases the risk of malfunctioning and reduces reliability.